The American Practical Navigator, first published in 1802, was billed as the “epitome of navigation” by its original author, Nathaniel Bowditch, an early American mathematician who is often considered the founder of modern maritime navigation. The text, often colloquially referred to simply as “Bowditch,” has evolved with the advances in navigation practices since that first issue and continues to serve as a valuable reference for marine navigation in the modern day. In the more than 210 years since Bowditch first published it, there have been an estimated million copies in print over the course of more than fifty editions. This latest edition—fully updated by the U.S. government to reorganize the topics, delete obsolete text, and incorporate the extensive changes in navigation that have occurred in the electronic age—remains popular with sailors of all types, is carried onboard every commissioned U.S. Navy vessel, and belongs in every navigator’s library. The American Practical Navigator describes in detail the principles and factors of navigation, including piloting, electronic navigation, celestial navigation, mathematics, safety, oceanography, and marine meteorology. It also contains a maritime glossary and dozens tables used in typical navigational calculations and solutions, including the formulas used to derive the tabular data. “Bowditch” is a must-have book for every mariner.

This 2019 edition of The American Practical Navigator (Bowditch), Pub No. 9, exists to codify the latest body of marine navigation knowledge and practical application. Its publication success is a result of the dedicated efforts of many hands and voices from academia, science and seafaring experts. This edition has advanced from the judiciously shaped recommendations-some comprehensive, some minute, all indispensable-of a multitude of maritime and science professionals. At the same time, it was equally essential that those recommendations be compared, vetted, and applied in a consistent manner and with a clear vision, a challenging task performed in exemplary fashion by this edition's principal editor, Dr. Gerard J. Clifford, Jr.